There is conventionally known an electronic control unit that reads and executes an instruction stored in a memory unit to control apparatuses associated with a vehicle body such as lighting apparatuses and power windows (see patent literature 1).
This type of electronic control units may use a dual core lockstep system to reduce unforeseeable risks caused by malfunction of the electronic control unit (i.e., to ensure the functional safety).
The electronic control unit based on the dual core lockstep system is mainly configured as a microcomputer including two arithmetic units. The two arithmetic units each execute the same instruction at the same time. An error is assumed to occur in the electronic control unit if a mismatch is found in operation results from the arithmetic units. The electronic control unit may need to be restarted or notify an error occurrence.